Do the wires from the front power stage connector on my '96 960 go directly to the coil packs? If so, which wires run coil #5? I'm getting a check engine light, OBDII code for cylinder 5 missfire, rough running. I replaced the spark plug, coil pack, front power stage ignition module but none of that has corrected the problem. Could there be a broken wire? Do both wires from the coil run to the power stage connector? Thanks.

The front PS controls cylinders 1,3 & 5. The rear PS controls cylinders 2,4 & 6.

DEWFPO
--
1998 S90 088,900 and 1995 964 154,100

Update: I checked the coil pack with the car running and get 12v at both wires in the connector. I also swapped the #1 coil pack with the #5 coil pack, car still runs rough and when I disconnect the wires to the #5 cylinder coil (while it's running) there is no change in the idle of the car.

Swap the front power stage with the rear stage and see if the miss moves the missing cylinder. If so, then you know it is a power stage, if not, then do a compression test. It could be a bad valve. Yes, it could still be the wire to the coil from the power stage, but if that is the case, it usually shows itself in the area on top of the head, look for worn insulation.

DanR '94 964 383,000 miles (149,000 on the new engine)
--
DanR

I'm 1600 miles from home and my compression tester. I could buy a new one, but I'm not going to be able to do anything here if it is a bad valve. The car runs relatively well at 70-75 mph. What sort of additional damage am I going to do if I drive it back home with no compression on one cylinder? I already drove it 1300 miles here in that condition and did not see any drop-off in mileage or oil consumption and no increased operating temp.

Did you swap the power stages? When mine broke an exhaust valve, I only had to drive 300 miles, but I disconnected the fuel injector plug to that cylinder.

I didn't have any problems but it was only 300 miles.

Good luck, keep us up on it.

DanR
--
DanR

With the plug firing, should I still disconnect he injector? Did you repair the broken exhaust valve or change the engine?

I missed the part where you replaced the power stage and it still had the same miss. But you can detect a spark, so maybe the injector is not firing? The spark may be too weak?

Another thing, the miss maybe because of an intake gasket leak. That can cause a miss at idle, that will even out a little when throttle is increased. Maybe the leak is small enough so that is how it is playing out?

Do you have any diagnosic engine codes?

On mine, I just replaced the valve, that was about 100,000 miles ago.

DanR
--
DanR

I only got a glance at the code when the guy from OReilly's pulled it. I think it was p305 and he said it was a miss-fire on #5. When I checked the spark, I used a new plug, then after seeing a nice blue spark, I pulled the plug from the cylinder (which I left in place while testing the coil) and could smell gasoline on the tip, so I suspect the injector is firing.
I tightened the intake bolts that I could see (only 4).

Hi Martin,

Hope that you have this sorted out by now, but in case you do not....A P0305 DTC is set when the crank sensor senses a disparity in rotational frequency of the particular cylinder, in this case #5. That can be caused by any of the traditional reasons...compression, ignition or fuel/air. Check compression first as you mentioned that your fuel mileage seems unchanged and that the vehicle runs reasonably well at 70mph+. That suggests that you have a marginal compression issue at idle which corrects itself as engine speed increases. Below 70psi you will get incomplete or no combustion. You might have a vacuum leak, maybe at the injector seal. Check with a bottle of MAPP or propane gas directed at the manifold or injector while running. Please do not use carb spray or ether. From your description the malfunction does not appear to be ignition related. Hope you get home safely.

Best Regards

pat hayes [wharfrat]

I checked the compression this morning after arriving home. #1=220#, #2=220#, #3=220#, #4=210#, #5=0#!!!, #6=230#. Sounds like a valve since it's not using any oil. What's my next step? Remove head? Replace engine (uses 1 qt/600mi)?
Marlin

Hi Martin,

The head will likely require removal and service, but just in case pull the valve cover and visually inspect the valve train for #5. It is always possible, though not likely, that a valve has hung up due to broke spring, keepers or adjuster. It's worth a look.

As far as a valve job...DIY $300 and a weekend, machine shop $500-$800 depending on condition and a week. DIY is time consuming but not technically difficult.

Best Regards

pat hayes

The head will need to be pulled, but it may not be all that bad, maybe 25.00 for a valve and a gasket/seal kit another 225.00 and about 10-14 hours of time. This all depends on the condition of the engine, oil usage? Those other compression numbers are not bad. Did you try squirting a little engine oil into the cylinders and see if they increased at all?

I have done a head replacement 3 times and never use a special volvo tool, it can be worked around, it you can get your hands on them of course do, it will make the job less stressful and quicker.

If the car is worth the added cost, send head to a machine shop and have them replace all the dress the valve and seats and replace the valve seals. Again only if it makes sense.

Dan
--
DanR

The salvage yard called to say the replacement engine had cracked oil pan & valve cover, so I'm going to pull the head. Do I have AllData, but not the green manuals. Dis-assembly seems straight-forward, but what's the procedure to align crank, cams & cam gears for re-assembly?
Marlin

Before you disassemble, place the cams and the crank on their marks, just as one would do for a timing belt change. This NOT TDC. You do not want it at TDC, having everything on their marks will drop all pistons to various positions below the deck. That way you can rotate cams without contacting a piston, at TDC that would be a problem.

The items to look out for, the 14mm bolt at the bottom of the intake manifold, the bottom of the bulbous part, is a bear to reach and just needs to be loosened, there is a slot on the bottom of the intake that allow for it to just slide out, so you don't have to spend all that time turning that one bolt.

If you have access to a welder, you could make your own head top hold down/break open device, which also helps in getting the head top to seperate. It is made out of spark plug bottoms and threaded rod. But is not necessary.

You also must mark your cams, you will have to replace the seals so the cam timing belt gears will need to be removed, mark them as intake and exhaust but also mark the gears to the cams, there are three bolts so you need to mark before removal, it will ruin your day if don't. I mean the cam gear to cam, exact location, so the factory timing belt mark is in the correct relation to the came. Loosen those timing gear bolts while the timing belt is still on. There was factory paint on mine between lobes, red on one, blue on the other, my initial thought was red for exhaust, and blue for intake, but it was the opposite.

Getting the head top off you have to break loose the sealant/glue that holds it on. There are something like 52 bolts, these all will need to be removed and the head top will not want to come off, there are 3-4 pry spots to get a hefty flat blade screw driver, but do not use great force, the aluminum can crack. Just go slow and around the head several times.
Once the head top springs up, care needs to be taken on removing the top, lift at the front of the engine first, there are grooves that keep the cams in place, very small grooves that can crack easily. Also, use the same care and work from the front on the removal of the cams from the head, same grooves apply on the head surface.

Keep the lifters labeled and in oil during the tear down, they must go back in the same holes.

Cleaning the head and head top is tedious and time consuming, but it needs to be pristine when done, do not scratch the mating surfaces. Use soft utensils, no razor blades. I use chop stick that have been cut down, the bamboo seems to hold up for awhile.

On reassembly, use the volvo part only for the sealant (expensive), it uses the lack of oxygen to cure, so while it is open you don't have to worry about it setting up and gives you days to get the head top on. Only couple of hours to cure once you tighten it up. The cheaper aftermarket sealants have a clock and only give you about an hour. Use a small foam roller to apply a thin coat to both surfaces, do not gob it on. Use lubricant on the moving parts especially the cam journals. Keeping it away from the sealant, the sealant/glue not only keeps the engine oil from leaking down the outsides of the engine, but internally it keeps the oil in it's channels to feed the cam journals, so any gaps in coverage will allow engine oil to leak internally, lowering engine oil pressure and possibly starve a journal.

On the reassembly of the head top, I used four c-clamps on the corners, to bring the head top down and overpower the valve springs. This is where you need to make sure your crank is on it's mark, it won't conflict with any valves.
Just tighten down gradually.
Resist the temptation to use those 50 some head top bolts to bring down the head top against the valve springs, those fine threaded holes in the head will strip out quite easily. Do all of them in a gradual sequence, first just snug, then 1/2 the torque, starting in the center and working gradually forward and rearward alternately.

Use a quality impact quality socket and strong breaker bar with a pipe extension to break loose the head bolts. Some say to use new bolts, but my book allows for use of the old bolts only if they have not stretched to a certain specification. They are not cheap.

Even using caution on the torque of the bolts, some of them might strip out, a heli coil kit worked for me, there are other brands that might be better, these kits actually make the bolt stronger than it was originally.

Let me know if you have any other questions.

DanR
--
DanR

Do you have a part number for the cam cover sealant? Tasca's not being very
cooperative in getting me the info.
Thanks.
Marlin

Cam cover & cams are marked, labeled photographed and removed. Did you label the lifters with a sharpie or put them in a baggie with oil? Should I just loosen the Oetiker clamps on the intake and remove it so I don't have to disturb the intake gasket? Did you re-use the Oetiker clamps? New rubber sleeves? I got a new Craftsman 14mm deep well impact socket for the head bolts (after I get the intake & exhaust off). Thanks for all your help.
Marlin

I put the lifters in a flat rectangular cake pan with oil, just labeled the one end front.

The clamps can come off on the intake, you should get a new intake gasket with the head kit anyway so that will not matter. I did reuse the clamps too.

Good luck

DanR
--
DanR

Removed the head last night and found one exhaust valve had a piece broken off. Tomorrow I'll try to find someone to replace it and check the others. I'll call Tasca about gasket kit, cam cover sealer, & solvent to remove the old sealer.
Marlin

Does Volvo have a head kit with all the necessary gaskets & sealer? Do you have a part number(Tasca has not responded to my email about this)?
Marlin

Do you know the length limit on re-use of the head bolts? Is the head gasket similar to other head gaskets, or is it liquid like the top gasket? Thanks for all the help. I've been maintaining Volvos since 1985, but have never had to take a head off until now.
Marlin

It is a normal head gasket.

The head bolts maximum length is from my book is 158mm. That is for engines,
B6244, B6254 and B6304.

DanR
--
DanR

I read the head repair info in the FAQ and decided to try and find a replacement engine. A local salvage yard has a '96 engine and will deliver and pick up the old one for $850. How do I disconnect the electronics for the engine? The cable under the intake is hidden and feels inflexible? What are the lift points? Can I just un-mount the PS pump, Alt & A/C compressor and leave the connections to them intact?

I installed a new front powerstage and since the error was on cylinder #5 I did not swap the powerstages. Since I see no change in the idle when I disconnect cylinder 5, and see a blue spark when I put a plug in the #5 coil pack I felt the swap was unnecessary. Do you think I should still swap them?
Marlin